libnftnl  1.2.4
immediate.c
1 /*
2  * (C) 2012 by Pablo Neira Ayuso <pablo@netfilter.org>
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License as published
6  * by the Free Software Foundation; either version 2 of the License, or
7  * (at your option) any later version.
8  *
9  * This code has been sponsored by Sophos Astaro <http://www.sophos.com>
10  */
11 
12 #include <stdio.h>
13 #include <stdint.h>
14 #include <string.h>
15 #include <arpa/inet.h>
16 #include <errno.h>
17 #include "internal.h"
18 #include <libmnl/libmnl.h>
19 #include <linux/netfilter/nf_tables.h>
20 #include <libnftnl/expr.h>
21 #include <libnftnl/rule.h>
22 
24  union nftnl_data_reg data;
25  enum nft_registers dreg;
26 };
27 
28 static int
29 nftnl_expr_immediate_set(struct nftnl_expr *e, uint16_t type,
30  const void *data, uint32_t data_len)
31 {
32  struct nftnl_expr_immediate *imm = nftnl_expr_data(e);
33 
34  switch(type) {
35  case NFTNL_EXPR_IMM_DREG:
36  memcpy(&imm->dreg, data, sizeof(imm->dreg));
37  break;
38  case NFTNL_EXPR_IMM_DATA:
39  memcpy(&imm->data.val, data, data_len);
40  imm->data.len = data_len;
41  break;
42  case NFTNL_EXPR_IMM_VERDICT:
43  memcpy(&imm->data.verdict, data, sizeof(imm->data.verdict));
44  break;
45  case NFTNL_EXPR_IMM_CHAIN:
46  if (e->flags & (1 << NFTNL_EXPR_IMM_CHAIN))
47  xfree(imm->data.chain);
48 
49  imm->data.chain = strdup(data);
50  if (!imm->data.chain)
51  return -1;
52  break;
53  case NFTNL_EXPR_IMM_CHAIN_ID:
54  memcpy(&imm->data.chain_id, data, sizeof(uint32_t));
55  break;
56  default:
57  return -1;
58  }
59  return 0;
60 }
61 
62 static const void *
63 nftnl_expr_immediate_get(const struct nftnl_expr *e, uint16_t type,
64  uint32_t *data_len)
65 {
66  struct nftnl_expr_immediate *imm = nftnl_expr_data(e);
67 
68  switch(type) {
69  case NFTNL_EXPR_IMM_DREG:
70  *data_len = sizeof(imm->dreg);
71  return &imm->dreg;
72  case NFTNL_EXPR_IMM_DATA:
73  *data_len = imm->data.len;
74  return &imm->data.val;
75  case NFTNL_EXPR_IMM_VERDICT:
76  *data_len = sizeof(imm->data.verdict);
77  return &imm->data.verdict;
78  case NFTNL_EXPR_IMM_CHAIN:
79  *data_len = strlen(imm->data.chain)+1;
80  return imm->data.chain;
81  case NFTNL_EXPR_IMM_CHAIN_ID:
82  *data_len = sizeof(imm->data.chain_id);
83  return &imm->data.chain_id;
84  }
85  return NULL;
86 }
87 
88 static int nftnl_expr_immediate_cb(const struct nlattr *attr, void *data)
89 {
90  const struct nlattr **tb = data;
91  int type = mnl_attr_get_type(attr);
92 
93  if (mnl_attr_type_valid(attr, NFTA_IMMEDIATE_MAX) < 0)
94  return MNL_CB_OK;
95 
96  switch(type) {
97  case NFTA_IMMEDIATE_DREG:
98  if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0)
99  abi_breakage();
100  break;
101  case NFTA_IMMEDIATE_DATA:
102  if (mnl_attr_validate(attr, MNL_TYPE_BINARY) < 0)
103  abi_breakage();
104  break;
105  }
106 
107  tb[type] = attr;
108  return MNL_CB_OK;
109 }
110 
111 static void
112 nftnl_expr_immediate_build(struct nlmsghdr *nlh, const struct nftnl_expr *e)
113 {
114  struct nftnl_expr_immediate *imm = nftnl_expr_data(e);
115 
116  if (e->flags & (1 << NFTNL_EXPR_IMM_DREG))
117  mnl_attr_put_u32(nlh, NFTA_IMMEDIATE_DREG, htonl(imm->dreg));
118 
119  /* Sane configurations allows you to set ONLY one of these two below */
120  if (e->flags & (1 << NFTNL_EXPR_IMM_DATA)) {
121  struct nlattr *nest;
122 
123  nest = mnl_attr_nest_start(nlh, NFTA_IMMEDIATE_DATA);
124  mnl_attr_put(nlh, NFTA_DATA_VALUE, imm->data.len, imm->data.val);
125  mnl_attr_nest_end(nlh, nest);
126 
127  } else if (e->flags & (1 << NFTNL_EXPR_IMM_VERDICT)) {
128  struct nlattr *nest1, *nest2;
129 
130  nest1 = mnl_attr_nest_start(nlh, NFTA_IMMEDIATE_DATA);
131  nest2 = mnl_attr_nest_start(nlh, NFTA_DATA_VERDICT);
132  mnl_attr_put_u32(nlh, NFTA_VERDICT_CODE, htonl(imm->data.verdict));
133  if (e->flags & (1 << NFTNL_EXPR_IMM_CHAIN))
134  mnl_attr_put_strz(nlh, NFTA_VERDICT_CHAIN, imm->data.chain);
135  if (e->flags & (1 << NFTNL_EXPR_IMM_CHAIN_ID)) {
136  mnl_attr_put_u32(nlh, NFTA_VERDICT_CHAIN_ID,
137  htonl(imm->data.chain_id));
138  }
139 
140  mnl_attr_nest_end(nlh, nest1);
141  mnl_attr_nest_end(nlh, nest2);
142  }
143 }
144 
145 static int
146 nftnl_expr_immediate_parse(struct nftnl_expr *e, struct nlattr *attr)
147 {
148  struct nftnl_expr_immediate *imm = nftnl_expr_data(e);
149  struct nlattr *tb[NFTA_IMMEDIATE_MAX+1] = {};
150  int ret = 0;
151 
152  if (mnl_attr_parse_nested(attr, nftnl_expr_immediate_cb, tb) < 0)
153  return -1;
154 
155  if (tb[NFTA_IMMEDIATE_DREG]) {
156  imm->dreg = ntohl(mnl_attr_get_u32(tb[NFTA_IMMEDIATE_DREG]));
157  e->flags |= (1 << NFTNL_EXPR_IMM_DREG);
158  }
159  if (tb[NFTA_IMMEDIATE_DATA]) {
160  int type;
161 
162  ret = nftnl_parse_data(&imm->data, tb[NFTA_IMMEDIATE_DATA], &type);
163  if (ret < 0)
164  return ret;
165 
166  switch(type) {
167  case DATA_VALUE:
168  /* real immediate data to be loaded to destination */
169  e->flags |= (1 << NFTNL_EXPR_IMM_DATA);
170  break;
171  case DATA_VERDICT:
172  /* NF_ACCEPT, NF_DROP, NF_QUEUE and NFTNL_RETURN case */
173  e->flags |= (1 << NFTNL_EXPR_IMM_VERDICT);
174  break;
175  case DATA_CHAIN:
176  /* NFTNL_GOTO and NFTNL_JUMP case */
177  e->flags |= (1 << NFTNL_EXPR_IMM_VERDICT) |
178  (1 << NFTNL_EXPR_IMM_CHAIN);
179  break;
180  }
181  }
182 
183  return ret;
184 }
185 
186 static int
187 nftnl_expr_immediate_snprintf(char *buf, size_t remain,
188  uint32_t flags, const struct nftnl_expr *e)
189 {
190  struct nftnl_expr_immediate *imm = nftnl_expr_data(e);
191  int offset = 0, ret;
192 
193  ret = snprintf(buf, remain, "reg %u ", imm->dreg);
194  SNPRINTF_BUFFER_SIZE(ret, remain, offset);
195 
196  if (e->flags & (1 << NFTNL_EXPR_IMM_DATA)) {
197  ret = nftnl_data_reg_snprintf(buf + offset, remain, &imm->data,
198  flags, DATA_VALUE);
199  SNPRINTF_BUFFER_SIZE(ret, remain, offset);
200 
201  } else if (e->flags & (1 << NFTNL_EXPR_IMM_VERDICT)) {
202  ret = nftnl_data_reg_snprintf(buf + offset, remain, &imm->data,
203  flags, DATA_VERDICT);
204  SNPRINTF_BUFFER_SIZE(ret, remain, offset);
205 
206  } else if (e->flags & (1 << NFTNL_EXPR_IMM_CHAIN)) {
207  ret = nftnl_data_reg_snprintf(buf + offset, remain, &imm->data,
208  flags, DATA_CHAIN);
209  SNPRINTF_BUFFER_SIZE(ret, remain, offset);
210  }
211 
212  return offset;
213 }
214 
215 static void nftnl_expr_immediate_free(const struct nftnl_expr *e)
216 {
217  struct nftnl_expr_immediate *imm = nftnl_expr_data(e);
218 
219  if (e->flags & (1 << NFTNL_EXPR_IMM_VERDICT))
220  nftnl_free_verdict(&imm->data);
221 }
222 
223 struct expr_ops expr_ops_immediate = {
224  .name = "immediate",
225  .alloc_len = sizeof(struct nftnl_expr_immediate),
226  .max_attr = NFTA_IMMEDIATE_MAX,
227  .free = nftnl_expr_immediate_free,
228  .set = nftnl_expr_immediate_set,
229  .get = nftnl_expr_immediate_get,
230  .parse = nftnl_expr_immediate_parse,
231  .build = nftnl_expr_immediate_build,
232  .output = nftnl_expr_immediate_snprintf,
233 };